The following invention relates to generally to thread repairs in machinery, particularly cast metal machines. More specifically, the instant invention is directed to a thread repair sleeve having a substantially cylindrical shape and interior and exterior threads used to replace damaged threads in a casting. The focal point is prevention of removal of the insert once installed.
Conventional repair techniques for stripped threads includes retapping the thread. While this type of repair is effective in some situations, grossly damaged threads are usually replaced with new threads defining a larger diameter bore. This, of course, necessitates the utilization of a larger fastener within the newly threaded bore which is undesirable particularly when the element to be inserted within the threaded bore is standardized, such as a spark plug.
The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant""s acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed.
Keen-Serts(copyright) advertisement, Solid Inserts, 1996, entire advertisement.
Heli-Coil advertisement, Screw Thread Inserts, 1998, entire advertisement.
The instant invention resolves the problems noted hereinabove and others by the provision of an insert which threads into new threads formed within the bore that is being repaired. The insert is a substantially cylindrical construct having an exterior thread which meshes with the newly threaded bore of the casting and an interior bore having threads complemental to the dimension of the preexisting fastener previously residing within the old bore. In this way, the same sized fastener or spark plug that was installed originally within the metal casting can be used after the repair. Besides fasteners and spark plugs, the insert also finds utility, inter alia, for repairing hydraulic fitting threads, pipe threads and as a blind hole insert.
Moreover, the instant invention addresses and resolves any problems associated with an attempt to subsequently remove the fastener or spark plug after the repair. In some situations, typically harsh operating environments involving corrosion or galvanic attraction between the various components of a system, the mating area between the threads of the fastener or spark plug can become seized to the insert. When this occurs, an attempt to remove the fastener or spark plug can sometimes cause rotation of the insert in conjunction with the fastener or spark plug, thwarting removal of the fastener or the spark plug alone. The probability of this occurring according to the present invention is substantially nil. The solution preferably includes the utilization of both specially formed threads and a shoulder on the insert which is adapted to provide a cylindrical bore strategically located to vertically align with the meshing exterior threads of the insert and the threads formed in the bore of the material being worked on. A top surface of the insert""s shoulder includes a cylindrical bore. After the insert has been placed within the material to be repaired, a hole may be drilled extending the cylindrical bore into the juncture of the exterior threads of the insert and the threads of the bore in the material. Finally, a cylindrical pin is driven into the cylindrical bore through the shoulder and into the drilled area of the exterior threads of the insert and the threads of the bore of the material so that the insert will no longer readily move with respect to the material because the flight of the threads of the insert on an exterior surface thereof will be opposed by the placement of the cylindrical pin and its retention by the threads of the bore of the material.
Where the insert already includes a vertical channel defining a thread gap aligned with the cylindrical bore of the insert""s shoulder, the drilling step is not mandatory. In this case, driving the cylindrical pin will actually improve insert retention because the threads in the bore contacted by the pin distort and therefore enhance retention of the insert in the bore.
Accordingly, a primary object of the present invention is to provide a threaded insert which resists removal once installed in a repair.
A further object of the present invention is to provide an insert which is not necessarily used in a repair, but instead provides a material of a different characteristic than the surrounding material within which it is threaded which resists dislodgment once installed. For example, the instant invention can be a relatively hard steel threaded into a relatively soft material such as aluminum to provide superior gripping and a more beneficial characteristic with the fastener or spark plug located within the interior threads of the insert.
A further object of the present invention is to provide a device as characterized above which is easy to install, difficult to remove and durable in construction.
A further object of the present invention is to provide a device as characterized above which is economical to manufacture and provides an economical solution to repairing objects which heretofore had to be discharged as unrepairable.
A further object of the present invention is to provide a device as characterized above which allows a fastener or spark plug of original dimension to be reinstalled in a bore after repair.
A further object of the present invention is to provide a device as characterized above which can be used with other fittings, such as hydraulic or pipe fittings and in blind bores.
A further object of the present invention is to provide a method for repairing or fabricating a receiving area for fasteners or spark plugs which includes the steps of providing a thread within a bore to receive. the insert, installing the insert into the threaded, bore, fixing the insert into the bore to preclude further rotation, and installing a fastener or spark plug in the bore.
Viewed from a first vantage point, it is an, object of the present invention to provide an insert, comprising, in combination: a sleeve, an exterior thread formed on the sleeve, an interior thread formed in the sleeve, a shoulder on one end of the sleeve, a bore in the shoulder axially aligned with the exterior thread, and a pin passing through the bore.
Viewed from a second vantage point, it is an object of the present invention to provide a method for repairing or fabricating a receiving area for an object, the steps including: providing a thread within a bore to receive an insert, threading the insert into the threaded bore, fixing the insert into the bore to preclude further rotation of the insert, and installing the object in the insert.
Viewed from a third vantage point, it is an object of the present invention to provide a device for providing a lining in an object, comprising, in combination: a sleeve having an exterior diameter substantially complemental to a bore in the object to be lined, a peripheral shoulder emanating from one end of the sleeve, a pin dimensioned to lodge in the shoulder and along an interface between the sleeve and the bore.
Viewed from a fourth vantage point, it is an object of the present invention to provide a sleeve having an interior thread and an exterior thread, the exterior thread includes a vertically aligned clearance to receive a pin therewithin.
Viewed from a fifth vantage point, it is an object of the present invention to provide a n insert, comprising, in combination: a sleeve having interior and exterior threads, a shoulder on one end of the sleeve having a hole passing therethrough, clearance in the exterior threads aligned with the hole, and a pin dimensioned to pass through the hole and reside within the clearance.
These and other objects will be made manifest when considering the following detailed specification when taken in conjunction with the appended drawing Figures.